Method and apparatus for cooling concrete during curing

ABSTRACT

A system and method for cooling a concrete slab to improve curing in hot weather includes a portable liquid cooler. A conduit is connected to the liquid cooler and arranged in proximity to the concrete slab. A pump is operative to circulate liquid from the liquid cooler through the conduit such that liquid moves from a supply port of the liquid cooler into an input end of the conduit at a supply temperature, moves through the conduit, and moves from an output end of the conduit to a return port of the liquid cooler at a return temperature greater than the supply temperature. Heat is absorbed from the concrete slab and the temperature of the slab is thus reduced compared to a slab in ambient hot weather conditions.

This invention is in the field of laying concrete, and particularly laying concrete in warm weather.

BACKGROUND

Maintaining the temperature of concrete at a satisfactory level during curing presents considerable challenges because of the wide ambient temperatures encountered when laying concrete. The American Society for Concrete Contractors recommends that the temperature of the concrete be maintained between 50 and 70° F. It is well known that concrete must be kept above freezing during curing when the weather is cold.

Similarly, when the weather is hot, the concrete can dry too quickly. As happens with concrete that freezes before curing, concrete that is too warm dries too quickly and so suffers from reduced strength and is subject to cracking. This problem is exacerbated by the heat generated within a freshly poured concrete slab, wall or the like by the chemical reactions of the curing process.

Proper curing of concrete can affect the final strength by several-fold, and so significant attention is paid to maintaining a desirable temperature and level of hydration of the freshly poured concrete in order that the curing process will be the most effective, and the finished concrete product will display the highest degree of strength.

It is well known to circulate hot liquid, such as hot water or a water/glycol mix, through a conduit arranged on a freshly laid concrete surface in order to prevent the concrete from freezing, and maintain the concrete at a temperature within the preferred temperature range for curing. Typically the conduit comprises flexible hoses are laid out in a back and forth pattern on the surface, with a spacing of 30-60 centimeters. It is also known to embed the hoses in the concrete to increase efficiency by better retaining and distributing the heat in the concrete. These hoses then remain in the finished concrete and are sacrificed, or in some cases are used to heat the finished building by circulating hot water through them.

In hot climates, ice is sometimes mixed with the concrete to reduce the temperature. Also it is known to circulate carbon dioxide gas through hoses similar to the above in order to cool the concrete.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method and apparatus for cooling concrete in hot weather that overcomes problems in the prior art.

In a first embodiment the invention provides a system for cooling a concrete slab to improve curing in hot weather. The system comprises a portable liquid cooler. A conduit is connected to the liquid cooler and adapted to be arranged in proximity to the concrete slab. A pump is operative to circulate liquid from the liquid cooler through the conduit such that liquid moves from a supply port of the liquid cooler into an input end of the conduit at a supply temperature, moves through the conduit, and moves from an output end of the conduit to a return port of the liquid cooler at a return temperature greater than the supply temperature.

In a second embodiment the invention provides a method of cooling a concrete slab to improve curing in hot weather. The method comprises providing a portable liquid cooler adjacent to the concrete slab, and connecting a conduit the liquid cooler and arranging the conduit in proximity to the concrete slab. With a pump, liquid is circulated from the liquid cooler through the conduit such that liquid moves from a supply port of the liquid cooler into an input end of the conduit at a supply temperature, moves through the conduit, and moves from an output end of the conduit to a return port of the liquid cooler at a return temperature greater than the supply temperature.

The liquid circulating through the conduit adjacent to the concrete slab absorbs heat from the slab and reduces the temperature of the slab. Drying of the concrete is slowed to improve curing and increase the strength of the finished slab.

DESCRIPTION OF THE DRAWINGS

While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:

FIG. 1 is a schematic top view of a system of the invention for cooling a concrete slab to improve curing in hot weather using a single conduit;

FIG. 2 is a schematic top view of a system of the invention for cooling a concrete slab to improve curing in hot weather using manifolds connected to a plurality of conduits.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 1 schematically illustrates a system for cooling a concrete slab 2 to improve curing in hot weather. The system comprises a portable liquid cooler 4 having a supply port 6 and a return port 8. The cooler 4 is conveniently an absorption chiller that is conveniently portable and can be operated on fuel such as diesel or propane such that a significant electrical power supply is not required. The cooler 4 is operative to cool liquid entering the return port 8 such that the temperature of the liquid entering the return port 8 is greater than the temperature of liquid leaving the supply port 6.

A conduit 10 is connected to the supply and return ports 6, 8 of the liquid cooler 4 and is arranged in proximity to the concrete slab 2. In the system illustrated in FIG. 1 the conduit 10 is flexible and arranged in loops on the surface of the concrete slab 2. Alternatively the conduit 10 could be embedded in the concrete slab 2. Once the concrete has cured, the liquid cooler 4 is disconnected from the conduit 10, which is then left in place.

A pump 12 is operative to circulate liquid from the supply port 6 of the liquid cooler 4 into an input end of the conduit 10 at a supply temperature, through the conduit 10, and from an output end of the conduit 10 to the return port 8 of the liquid cooler 4 at a return temperature that is greater than the supply temperature.

The cool liquid entering the conduit absorbs heat from the concrete slab as it moves through the conduit 10 such that the temperature thereof increases between the input and output ends of the conduit 10. As the liquid passes through the cooler 4, the temperature of same is reduced to the supply temperature. The system essentially pumps heat out of the concrete to maintain the concrete slab 2 at a reduced temperature compared to the ambient temperature. Drying time and curing time thus increase, improving the strength of the concrete slab 2.

For best results a blanket or like insulation layer will typically be spread over the conduit 10 and concrete slab 2 in order to reduce the amount of heat absorbed by the cooled liquid from the atmosphere, and thus increase the amount of heat absorbed from the slab 2.

FIG. 2 illustrated the system of FIG. 1 with the addition of a supply manifold 20A operatively connected to the supply port 6 of the liquid cooler 4, and a return manifold 20B operatively connected to the return port 8 of the liquid cooler 4. A plurality of conduits 10 each has an input end 10A operatively connected to the supply manifold 20A and an output end 10B operatively connected to the return manifold 20B.

Thus in the system of FIG. 2, cooled liquid enters the input ends 10A of each conduit 10 at the supply temperature and leaves the output ends 10B thereof at the return temperature. The capacity of the pump 12 is increased such that, for example, where the pump 12 in FIG. 1 might pump 100 liters per minute (l/m) through the single conduit 10, the pump 12 in FIG. 2 would pump 200 l/m to the supply manifold 20A, and each conduit 10 would carry 100 l/m to the return manifold 20B such that 200 l/m is returned to the return port 8. Thus the liquid moves through the conduits 10 at the same speed as in FIG. 1, but for a shorter distance such that liquid in each conduit 10 absorbs less heat before returning to the return port 8 and the temperature increase of the liquid is therefore reduced, and the return temperature is less than it is in the system of FIG. 1. 

1. A system for cooling a concrete slab to improve curing in hot weather, the system comprising: a portable liquid cooler; a conduit connected to the liquid cooler and adapted to be arranged in proximity to the concrete slab; a pump operative to circulate liquid from the liquid cooler through the conduit such that liquid moves from a supply port of the liquid cooler into an input end of the conduit at a supply temperature, moves through the conduit, and moves from an output end of the conduit to a return port of the liquid cooler at a return temperature greater than the supply temperature.
 2. The system of claim 1 wherein the conduit is flexible and adapted to be arranged in loops on a surface of the concrete slab.
 3. The system of claim 1 wherein the conduit is adapted to be arranged in loops and embedded in the concrete slab.
 4. The system of claim 1 further comprising: a first manifold operatively connected to the supply port of the liquid cooler; a second manifold operatively connected to the return port of the liquid cooler; a plurality of conduits each having an input end operatively connected to the first manifold and an output end operatively connected to the second manifold.
 5. The system of claim 1 wherein the portable liquid cooler comprises an absorption chiller.
 6. The system of claim 1 comprising an insulation layer configured to substantially cover the concrete slab.
 7. A method of cooling a concrete slab to improve curing in hot weather, the method comprising: providing a portable liquid cooler adjacent to the concrete slab; connecting a conduit the liquid cooler and arranging the conduit in proximity to the concrete slab; with a pump, circulating liquid from the liquid cooler through the conduit such that liquid moves from a supply port of the liquid cooler into an input end of the conduit at a supply temperature, moves through the conduit, and moves from an output end of the conduit to a return port of the liquid cooler at a return temperature greater than the supply temperature.
 8. The method of claim 7 wherein the conduit is flexible and arranged in loops on a surface of the concrete slab.
 9. The method of claim 7 wherein the conduit is arranged in loops and embedded in the concrete slab.
 10. The method of claim 7 further comprising: providing a first manifold operatively connected to the supply port of the liquid cooler; providing a second manifold operatively connected to the return port of the liquid cooler; providing a plurality of conduits each having an input end operatively connected to the first manifold and an output end operatively connected to the second manifold, and circulating liquid from the supply port of the liquid cooler into the first manifold to the input end of each conduit, through each conduit, and from the output end of the conduit to the return port of the liquid cooler.
 11. The method of claim 7 wherein the portable liquid cooler comprises an absorption chiller.
 12. The method of claim 7 comprising covering the concrete slab with an insulation layer. 